The present invention relates to an apparatus for detecting the amount of the rolled paper remaining in a roll of paper used in a facsimile apparatus, an electrophotographic copying machine or the like.
In a facsimile apparatus employing rolled recording paper or an electrophotographic copying machine employing rolled transfer paper or photosensitized paper, an apparatus for detecting the amount of the remaining paper is required.
Various types of apparatus for detecting the amount of paper remaining on a paper roll have been proposed, and some of these devices are used in practice.
In a facsimile apparatus employing rolled roll at reception of information, and is recording paper roll at each reception of information and is used for the recording of information until the rolled paper comes to an end. For use with such a facsimile apparatus, on apparatus for feeding a new roll of paper or for preventing a shortage of rolled paper during the information reception is known. In such apparatus, the diameter of the paper roll is detected to determine the amount of remaining paper on the principle that the diameter of the paper roll decreases as the paper is consumed. More specifically, in typical apparatus for detecting the amount of rolled paper remaining on a paper roll, a detection member is disposed in contact with a portion on the outer peripheral surface of the paper roll, and the displacement of the detection member is mechanically detected during the operation of the facsimile apparatus. Upon displacement of the detection member to a predetermined position, a warning of a low supply of paper is given by an indicator potion to attract the operator's attention. Alternatively, a detection member is disposed in contact with the outer peripheral surface of paper roll. As the paper is used and the diameter of the paper roll decreases, the detection member moves between a light emitting element and a light receiving element, intercepting the optical path between that two elements and causing some change in electric current flowing in an electric circuit, whereby the remaining amount of the rolled paper is detected and the detected amount is displayed, or an alarm indicating the remaining amount of the paper is low is given to the operator.
The first-mentioned mechanical detection system will work well when the detection member and the indicator portion are located relatively close to each other. However, when the two portions are located relatively far apart from each other, a complicated mechanism for connecting the two portions will be required. That requirement can be a drawback of the mechanical detection system.
In contrast with this, the second-mentioned detection system employing a light emitting element and a light receiving element will present little problems even if the remaining amount detecting portion and the remaining amount indicating portion (or alarm portion) are located far apart. However, the components required for that system are relatively expensive. Furthermore, it is required that the system be strictly protected from dust, since that system is vulnerable to dust which may be deposited on any of the light elements making accurate light measurement difficult, causing malfunction of the system.